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Are You Getting Enough Vitamin D?

A geriatrician describes her healthy aging dose for preventing a deficiency

By Leslie Kernisan, MD

(This article appeared previously on

Confused by all the back and forth in the media about vitamin D?

Don’t be. In this post, I’ll explain what is currently recommended for older adults. And I’ll tell you why I recommend vitamin D to most of my own patients. I’ll also address some frequently asked questions about it.

My Recommended Vitamin D Dose for Older Adults

For most older adults, I recommend a supplement of vitamin D (1,000 IU per day).

I do this because:

I also do this because:

  • Many older adults have risk factors for vitamin D deficiency. These include having osteoporosis and spending limited time outdoors.
  • Many older adults are at increased risk for falls.
  • In the vast majority of older people, taking vitamin D (1,000 IU) as a supplement every day has a very low risk of harm.

What Other Experts Say

Other expert groups have provided similar guidance. For instance, in 2010, the Institute of Medicine (now known as the Health and Medicine Division of the National Academies of Science, Engineering and Medicine) published a report with age-based Recommended Daily Allowances for vitamin D in “normal healthy persons.”

For people aged 1 to 70, it recommended 600 IU/day. For people aged 71+, it recommended 800 IU/day.

I think either 800 IU/day or 1,000 IU/day is fine. But I usually tell people 1,000 IU/day, since it’s a nice round number recommended by AGS. I call this the “healthy aging” dose of daily vitamin D.

People who are already taking a multivitamin or calcium supplement should check to see how much vitamin D is already included. They may already be getting 1,000 IU from those supplements.

Frequently Asked Questions About Vitamin D

Here are seven frequently asked questions about vitamin D and my answers:

1. Which type of vitamin D should I take?

Most supplements contain vitamin D3, also known as cholecalciferol. Studies suggest that this increases blood levels a little better than vitamin D2 (ergocalciferol).

Both versions require processing by the liver and kidneys. People with liver or kidney disease may need to get a special type of supplement from their doctors.

Although vitamin D supplements are usually taken daily, they also come in higher doses which may be prescribed for weekly or even monthly dosing. (These are available over-the-counter, but I think it’s best to take them under medical supervision.)

2. Do I need to have my vitamin D blood level checked?

Not necessarily. The AGS consensus statement says that testing vitamin D levels should be unnecessary in most older adults, unless some symptom or disease warrants it.

The idea is that if people take a daily vitamin D supplement as recommended above, they’ll be highly unlikely to have a level that is too low or too high.

On the other hand, if you have been diagnosed with a serious vitamin D deficiency, your doctor will likely recommend a higher dose. In this case, most experts recommend a repeat vitamin D blood test after three to four months of treatment. People with certain conditions may require a different type of test.

I do end up checking vitamin D levels sometimes in my practice. That's because many of my patients have severe osteoporosis, or sometimes an abnormal blood calcium level.

That said, I agree with those who say that vitamin D testing is often overused. But of all the tests and services to overuse, this one strikes me as fairly minor. If you’re worried about overtesting or overtreatment, it’s far more worthwhile to avoid unnecessary scans, procedures and medications.

3. Will vitamin D really prevent falls or fractures?

Good question. Some studies have suggested that vitamin D reduces the chance of these serious health events, but these results have been questioned by later studies.


My take is that vitamin D might help a bit, especially for certain seniors. Since it has a low chance of harm and probably helps some people somewhat, I recommend it.

However, I usually tell people to not have overly optimistic expectations of vitamin D’s effects. In most older adults, problems such as pain, fatigue and/or falls are due to multiple underlying causes, so there’s often no easy fix available.

4. Will vitamin D prevent dementia, cancer and/or premature death?

Several studies have identified an association between vitamin D deficiency and diagnoses such as Alzheimer’s disease and cancer. In other words, people with these conditions tend to have low vitamin D blood levels.

But an association isn’t the same thing as causation, so it’s not yet known whether vitamin D deficiency causes these diseases. It’s also not yet known whether taking vitamin D supplements will reduce one’s chance of developing these diseases.

In 2010, the Institute of Medicine concluded “This thorough review found that information about the health benefits [of vitamin D supplementation] beyond bone health — benefits often reported in the media — were from studies that provided often mixed and inconclusive results and could not be considered reliable.”

My take: Although the ongoing research is very interesting, I feel it’s unlikely to make practical changes to my practice. It’s possible that low vitamin D levels might be a factor in developing certain diseases, but it’s probably a small effect. Cancer and Alzheimer’s, after all, generally seem to be the result of lots of factors — genetics, epigenetics, stress, immune function, nutrition, inflammation, toxins — interacting over time.

Furthermore, taking a daily vitamin D supplement as recommended above should help most people avoid very low vitamin D levels.

5. I am outside a lot and I know you can get some vitamin D from the sun. Do I need a supplement?

Hard to say without checking your levels. In general, I recommend people take a daily vitamin D supplement no matter how much time they spend outside.

To begin with, it’s usually a good idea to wear sunscreen if you are going to be exposed to UV radiation, because skin cancer is common. Furthermore, even if you are getting enough vitamin D through sunlight or diet, taking a supplement of 1,000 IU is unlikely to raise your vitamin D levels to a problematic range.

In my view, people of all ages usually have plenty they can and should do for their health and their lives. Why spend much time figuring out vitamin D? Take whatever is recommended for your age (or by your doctor), and focus your energies on getting enough exercise, implementing other healthy habits, taking care of those who need you and managing any chronic conditions you have.

6. What should one’s vitamin D level be?

This question has been hotly, hotly debated. At this time, it depends on whom you ask.

The Health and Medicine Division of the National Academies of Science, Engineering and Medicine believes a blood level of 20 to 40 nanograms per milliliter (ng/mL) should be adequate. The Endocrine Society, the American Geriatrics Society, and some other expert groups recommend a level of at least 30 ng/mL.

7. I heard that a higher level of vitamin D is better for you. How much is too much?

Again, this depends on whom you ask. The American Geriatrics Society says for most people, total vitamin D (from supplements and food) shouldn’t exceed 4,000 IU/day.

Research into the risks of too much vitamin D is ongoing. A study of very high vitamin D supplementation (500,000 IU once a year) showed increased falls and fractures in older adults, so clearly it’s possible to have too much of a good thing.

I have also encountered a few patients with high blood calcium levels; they were taking high doses of the supplements and had fairly high blood levels of vitamin D. (Vitamin D is related to the absorption and metabolism of calcium in the body.) One of them went on to have a heart attack a few months later; his blood level of vitamin D had been about 70 ng/mL. This is a single case, but given that calcium supplements have been linked to heart attacks, I wonder if research won’t eventually confirm a link between high vitamin D blood levels and increased heart attack risk.

My own practice is to caution patients if they are taking daily vitamin D supplements of more than 2,000 IU/day in the absence of documented deficiency. I also discuss a reduction in the supplementation if a patient has a blood level greater than 50 ng/mL.

Leslie Kernisan, MD
Leslie Kernisan, MD, is a practicing geriatrician in San Francisco who believes that it shouldn’t be so hard for older adults and families to get the right kind of help with health concerns. She's the author of When Your Aging Parent Needs Help and the founder of the website and podcast Better Health While Aging and the Helping Older Parents online programs. Read More
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